Fender Stage DSP 100 amp crackling modulating noise issue

[la-2a]

Hello folks, after a successful repair of a Fender Stage 100 DSP, a small problem remained. As the guitar strings fade away, a quiet but disturbing modulating (crackling) clink and hiss can be heard. The preamp is ok and clean. When I spray Q11 with cold spray it disappears for a few seconds and then comes back again. I exchanged almost everything in the output amp. The driver transistors Q10, Q11 and Q12, Q13 are not hfe matched. Could this be my problem?? I am grateful for any suggestions.

 

[CJ]

First thing I would do us get out of he scope. If no scope then check voltages against schematic.

Maybe measure V e-b of the output transistors although some circuits have them biased to almost off.